Scipedia: Collection of restricted reports in transport research

YANG Data Model for Traffic Engineering (TE) Topologies

Scipedia content — Thu, 11 Feb 2021 14:13:44 +0100

This document defines a YANG data model for representing, retrieving and manipulating Traffic Engineering (TE) Topologies. The model serves as a base model that other technology specific TE Topology models can augment.

IS-IS Application-Specific Link Attributes

Scipedia content — Thu, 11 Feb 2021 14:18:44 +0100

Existing traffic engineering related link attribute advertisements have been defined and are used in RSVP-TE deployments. Since the original RSVP-TE use case was defined, additional applications (e.g., Segment Routing Policy, Loop Free Alternate) that also make use of the link attribute advertisements have been defined . In cases where multiple applications wish to make use of these link attributes, the current advertisements do not support application-specific values for a given attribute, nor do they support indication of which applications are using the advertised value for a given link. This document introduces new link attribute advertisements that address both of these shortcomings.

Impact of COVID-19 on Travel Behavior and Shared Mobility Systems

Scipedia content — Thu, 11 Feb 2021 14:19:20 +0100

Scenarios and Simulation Results of PCE in a Native IP Network

Scipedia content — Thu, 11 Feb 2021 14:27:50 +0100

Requirements for providing the End to End(E2E) performance assurance are emerging within the service provider networks. While there are various technology solutions, there is no single solution that can fulfill these requirements for a native IP network. In particular, there is a need for a universal (E2E) solution that can cover both intra- and inter-domain scenarios. One feasible E2E traffic engineering solution is the addition of central control in a native IP network. This document describes various complex scenarios and simulation results when applying the Path Computation Element (PCE) in a native IP network. This solution, referred to as Centralized Control Dynamic Routing (CCDR), integrates the advantage of using distributed protocols and the power of a centralized control technology, providing traffic engineering for native IP networks in a manner that applies equally to intra- and inter-domain scenarios.

STATISTICAL ANALYSIS OF DYNAMICAL QUANTITIES RELATED TO RUNNING SAFETY AND RIDE COMFORT OF A RAILWAY VEHICLE

Scipedia content — Thu, 11 Feb 2021 17:59:25 +0100

This paper investigates the variation of track geometrical parameters that lead to a local increase of specific dynamical quantities of a railway vehicle, possibly beyond their acceptable values. In particular, the changes of track geometry are investigated near track points where the running safety or ride comfort are significantly decreased during the vehicle motion due to track irregularities. The investigated dynamical quantities include the lateral and vertical forces at the wheel-rail contact as well as the acceleration of the vehicle body. The vehicle motion has been simulated using a non-linear model of a passenger car moving along a nominally tangent stiff track with random geometrical irregularities. The relationship between the local track condition and the maxima of the dynamical quantities was investigated with the statistical method proposed by the author. The performed analysis clearly identifies the characteristic variation of track irregularities that leads to a large increase of the investigated dynamical quantities at some track points.

Unsettled Topics in the Application of Satellite Navigation to Air Traffic Management

Scipedia content — Thu, 11 Feb 2021 14:33:52 +0100

Common YANG Data Types for Traffic Engineering

Scipedia content — Thu, 11 Feb 2021 14:37:35 +0100

This document defines a collection of common data types and groupings in YANG data modeling language. These derived common types and groupings are intended to be imported by modules that model Traffic Engineering (TE) configuration and state capabilities.

Ability for a Stateful Path Computation Element (PCE) to Request and Obtain Control of a Label Switched Path (LSP)

Scipedia content — Thu, 11 Feb 2021 14:39:20 +0100

Stateful Path Computation Element (PCE) retains information about the placement of Multiprotocol Label Switching (MPLS) Traffic Engineering Label Switched Paths (TE LSPs). When a PCE has stateful control over LSPs it may send indications to LSP head-ends to modify the attributes (especially the paths) of the LSPs. A Path Computation Client (PCC) that has set up LSPs under local configuration may delegate control of those LSPs to a stateful PCE. There are use-cases in which a stateful PCE may wish to obtain control of locally configured LSPs of which it is aware but that have not been delegated to the PCE. This document describes an extension to the Path Computation Element communication Protocol (PCEP) to enable a PCE to make requests for such control.

Avoiding Traffic Congestion Externalities? The Value of Urgency

Scipedia content — Thu, 11 Feb 2021 14:43:15 +0100

In Becker (1965) and neoclassical microeconomic theory the value of time is a constant fraction of the hourly wage. When taken to data, however, this value departs from theoretical predictions, and appears to vary with the amount of time saved. By observing drivers on freeways opting to enter toll lanes with high-frequency, time-varying prices that secure a minimum level-of-service, we uncover a new and fundamental aspect of preferences for travel time savings related to urgency. The presence of preferences for urgency, which reflect the fact that individuals often face discrete penalties for being late, allows us to reconcile the pattern observed in the data with neoclassical theory. Using a rich, repeated-transaction data and individual-level hedonic estimation, we show that the value of urgency accounts for 87 percent of total willingness-to-pay for time savings. As a result, ignoring the value of urgency in cost-benefit analysis severely underestimates the true value of time savings that projects deliver, as such omission will typically ignore non-trivial welfare gains to a potentially large number of individuals.